Nr1 (Based On A Line Enhancer) (Af Processing) - Kenwood TS-590SG Manual

The new spectral subtraction-based NR1 allows selection of the NR effect level more smoothly than the conventional NR1
method. Use the effect level of your choice according to the receive conditions.
Note, however, since the noise estimation process of the spectral subtraction NR1 identifies any steady sound as a noise
component, beat interference or a CW signal is also judged as a target of noise reduction. Meanwhile, the conventional
noise reduction (based on a line enhancer) functions to emphasize the beat interference or CW signal. Because the new
spectral subtraction-based NR1 is not intended for elimination of a CW signal or beat interference, you cannot expect a
noticeable effect against those signals. To remove the beat interference or CW signal, use Beat Cancel (BC) instead. The
analysis result of the frequency conducted on the receive audio containing an audio signal while NR1 is inactive is shown
in Figure 4-15, and the result while NR1 is active is shown in Figure 4-16.
Audio spectrum components swamped by noise
Figure 4-15 NR1 (Spectral
Subtraction Method) (Inactive)

4.6.5 NR1 (Based on a Line Enhancer) (AF Processing)

As a noise suppression process, the line enhancer method based on a DSP has been adopted by many amateur radio
transceivers in recent years. This method automatically adjusts the filter characteristics according to the characteristics of
a RX signal to obtain filter characteristics suitable for passing periodic signals such as a CW signal. Because the process
automatically passes and emphasizes the periodic signals, it is called a line enhancer (line spectrum enhancer). Since the
degradation of receive audio is small, a line enhancer is an easy-to-use, engineer-friendly technique. For the TS-590S/SG,
we have reviewed part of the NR1 process and succeeded in drastically improving the noise reduction capability compared
with previous models. The analysis result of the frequency conducted on the receive audio containing a sine wave while NR1
(based on a line enhancer) is inactive is shown in Figure 4-17, and the result while NR1 is active is shown in Figure 4-18.
Target signal
Figure 4-17 NR1 (Line Enhancer Method) (Inactive)
Audio spectrum components extracted by NR
Figure 4-16 NR1 (Spectral
Subtraction Method) (Active)
Target signal
Figure 4-18 NR1 (Line Enhancer Method) (Active)
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